Secondary carrier activation/deactivation method and apparatus for mobile communication system supporting carrier aggregation

ABSTRACT

A method for activating/deactivating secondary carriers of a User Equipment (UE) in a mobile communication system supporting carrier aggregation is provided. The method comprises, receiving a control message including an activation/deactivation Control Element (CE) in a first sub-frame from a Base station, identifying an activation command or a deactivation command of at least one secondary carrier based on the control message, determining whether a current sub-frame is a second sub-frame or not, performing at least one first operation for the at least one secondary carrier in a second sub-frame, and performing, when the activation/deactivation CE indicates deactivation of the at least one secondary carrier, at least one second operation for the at least one secondary carrier no later than the second sub-frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of prior application Ser. No.14/335,175, filed on Jul. 18, 2014, which is a continuation of priorapplication Ser. No. 14/243,453, filed on Apr. 2, 2014, which is acontinuation of prior application Ser. No. 13/347,961, filed on Jan. 11,2012, which claimed the benefit under 35 U.S.C. §119(e) of a U.S.Provisional application filed on Jan. 11, 2011 in the U.S. Patent andTrademark Office and assigned Ser. No. 61/431,635, and under 35 U.S.C.§119(a) of a Korean patent application filed on Dec. 26, 2011 in theKorean Intellectual Property Office and assigned Serial number10-2011-0141875, the entire disclosure of each of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mobile communication system. Moreparticularly, the present invention relates to a method foractivating/deactivating secondary carrier(s) in addition to a primarycarrier for the mobile communication system supporting carrieraggregation.

2. Description of the Related Art

With the rapid development of wireless communication technologies, LongTerm Evolution (LTE) is taking a strong position in 4^(th) Generation(4G) mobile communication technology. Various techniques have beenintroduced to meet the high capacity requirements of LTE. Carrieraggregation is a technique to increase the peak data rate and capacity,as compared to single carrier transmission, by aggregating one or moresecondary carriers with a primary carrier between User Equipment (UE)and an evolved Node B (eNB). In LTE, the primary carrier is referred toas Primary Cell (PCell) and the secondary carrier as Secondary Cell(SCell).

The carrier aggregation technique causes additional control complexityfor the PCell to control the SCells. This means that the PCell should beable to determine whether to use SCell and, if so, determine the SCellto be used. There is also a need for a method of activating anddeactivating SCells. This means that the actual operations of the UE inreceipt of SCell activation/deactivation command from the eNB should bespecified in detail.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide a method for activating and deactivating SCellin the mobile communication system supporting carrier aggregation.

Another aspect of the present invention is to provide a method foractivating and deactivating SCell in a mobile communication system thatis capable of initiating some operations with delay in activation of aSCell, terminating some operations in advance in deactivation of theSCell, and terminating some operations at a predetermined time.

In another aspect of the present invention, a method foractivating/deactivating secondary carriers of a User Equipment (UE) in amobile communication system supporting carrier aggregation is provided.The method comprises receiving a control message including anactivation/deactivation Control Element (CE) in a first sub-frame from aBase station, identifying an activation command or a deactivationcommand of at least one secondary carrier based on the control message,determining whether a current sub-frame is a second sub-frame or not,performing at least one first operation for the at least one secondarycarrier in a second sub-frame, and performing, when theactivation/deactivation CE indicates deactivation of the at least onesecondary carrier, at least one second operation for the at least onesecondary carrier no later than the second sub-frame

In yet another aspect of the present invention, a User Equipment (UE)for controlling activation/deactivation of secondary carriers in amobile communication system supporting carrier aggregation is provided.The UE comprises a transceiver configured to communicate signals with abase station, and a controller configured to receive a control messageincluding an activation/deactivation Control Element (CE) in a firstsub-frame from a Base station, to identify an activation command or adeactivation command of at least one secondary carrier based on thecontrol message, to determine whether a current sub-frame is a secondsub-frame or not, to perform at least one first operation for the atleast one secondary carrier in a second sub-frame, and to perform, whenthe activation/deactivation CE indicates deactivation of the at leastone secondary carrier, at least one a second operation for the at leastone secondary carrier no later than the second sub-frame.

In still another aspect of the present invention, a method foractivating/deactivating secondary carriers in a base station in a mobilecommunication system supporting carrier aggregation is provided. Themethod comprises configuring a control message including anactivation/deactivation Control Element (CE), theactivation/deactivation CE corresponding to activation/deactivation ofat least one secondary carrier, transmitting to the UE the secondarycarrier control message in a first subframe, receiving, when theactivation/deactivation CE indicates activation of the at least onesecondary carrier, a Channel State Information (CSI) report on the atleast one carrier in a second subframe, and receiving, when theactivation/deactivation CE indicates deactivation of the at least onesecondary carrier, a CSI report for the at least one secondary carrierno later than the second subframe.

In still another aspect of the present invention, a base station forcontrolling activation/deactivation of secondary carriers in a mobilecommunication system supporting carrier aggregation is provided. Thebase station comprises a transceiver configured to communicate signalswith a base station, and a controller configured to configure a controlmessage including an activation/deactivation Control Element (CE), theactivation/deactivation CE corresponding to activation/deactivation ofat least one secondary carrier, to transmit to the UE the controlmessage in a first subframe, to receive, when theactivation/deactivation CE indicates activation of the at least onesecondary carrier, a Channel State Information (CSI) report on the atleast one secondary carrier in a second subframe, and to receive, whenthe activation/deactivation CE indicates deactivation of the at leastone secondary carrier, a CSI report for the at least one carrier nolater than the second subframe.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagram illustrating the architecture of a mobilecommunication system according to an exemplary embodiment of the presentinvention;

FIG. 2 is a diagram illustrating a protocol stack of the mobilecommunication system according to an exemplary embodiment of the presentinvention;

FIG. 3 is a diagram illustrating an exemplary situation of carrieraggregation in the mobile communication system according to an exemplaryembodiment of the present invention;

FIG. 4 is a signaling diagram illustrating message flows between a UserEquipment (UE) and an evolved Node B (eNB) for a secondary carryactivation/deactivation method according to an exemplary embodiment ofthe present invention;

FIG. 5 is a flowchart illustrating a UE procedure for performing firstoperations in a secondary carrier activation/deactivation methodaccording to an exemplary embodiment of the present invention;

FIG. 6 is a flowchart illustrating a UE procedure for performing secondoperations in a secondary carrier activation/deactivation methodaccording to an exemplary embodiment of the present invention; and

FIG. 7 is a block diagram illustrating a configuration of a UE accordingto an exemplary embodiment of the present invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding, but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purposes only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Exemplary embodiments of the present invention relate to a secondarycarrier activation/deactivation method and apparatus of a UE in a mobilecommunication system supporting carrier aggregation.

FIG. 1 is a diagram illustrating the architecture of a mobilecommunication system according to an exemplary embodiment of the presentinvention.

Referring to FIG. 1, the radio access network of the mobilecommunication system includes evolved Node Bs (eNBs) 105, 110, 115, and120, a Mobility Management Entity (MME) 125, and a Serving-Gateway(S-GW) 130. The User Equipment (hereinafter, referred to as UE) 135connects to an external network via eNBs 105, 110, 115, and 120 and theS-GW 130.

The eNBs 105, 110, 115, and 120 correspond to legacy node Bs ofUniversal Mobile Communications System (UMTS). The eNBs 105, 110, 115,and 120 allow the UE establish a radio link and are responsible for morecomplicated functions than a legacy node B. In the LTE system, all theuser traffic including real time services such as Voice over InternetProtocol (VoIP) are provided through a shared channel. Accordingly,there is a need of a device which is located in the eNB to schedule databased on the state information such as UE buffer conditions, powerheadroom state, and channel state. Typically, one eNB controls aplurality of cells. In order to secure a data rate of up to 100 Mbps,the LTE system adopts Orthogonal Frequency Division Multiplexing (OFDM)as a radio access technology on 20 MHz bandwidth. The LTE system alsoadopts Adaptive Modulation and Coding (AMC) to determine the modulationscheme and channel coding rate in adaptation to the channel condition ofthe UE. S-GW 130 is an entity to provide data bearers so as to establishand release data bearers under the control of the MME 125. MME 125 isresponsible for various control functions and connected to a pluralityof eNBs 105, 110, 115, and 120.

FIG. 2 is a diagram illustrating a protocol stack of the mobilecommunication system according to an exemplary embodiment of the presentinvention.

Referring to FIG. 2, the protocol stack of the LTE system includesPacket Data Convergence Protocol (PDCP) 205 and 240, Radio Link Control(RLC) 210 and 235, Medium Access Control (MAC) 215 and 230, and Physical(PHY) 220 and 225. The PDCP 205 and 240 is responsible for IP headercompression/decompression. The RLC 210 and 235 is responsible forsegmenting the PDCP Protocol Data Unit (PDU) into segments in a sizeappropriate for Automatic Repeat Request (ARQ) operation. The MAC 215and 230 is responsible for establishing connection to a plurality of RLCentities so as to multiplex the RLC PDUs into MAC PDUs and demultiplexthe MAC PDUs into RLC PDUs. The PHY 220 and 225 performs channel codingon the MAC PDU and modulates the MAC PDU into OFDM symbols to transmitover radio channel or performs demodulating and channel-decoding on thereceived OFDM symbols and delivers the decoded data to the higher layer.

FIG. 3 is a diagram illustrating an exemplary situation of carrieraggregation in the mobile communication system according to an exemplaryembodiment of the present invention.

Referring to FIG. 3, an eNB typically uses multiple carriers transmittedand received in different frequency bands. For example, the eNB 305 maybe configured to use the carrier 315 with center frequency f1 and thecarrier 310 with center frequency f3. If carrier aggregation is notsupported, the UE 330 has to transmit/receive data using only one of thecarriers 310 and 315. However, the UE 330 having the carrier aggregationcapability may transmit/receive data using both the carriers 310 and315. The eNB may increase the amount of resources to be allocated to theUE having the carrier aggregation capability in adaptation to thechannel condition of the UE so as to improve the data rate of the UE.

When a cell is configured with one downlink carrier and one uplinkcarrier, the carrier aggregation may be understood as if the UEcommunicates data via multiple cells. With the use of carrieraggregation, the maximum data rate increases in proportion to the numberof aggregated carriers.

In the following description, the phrase “the UE receives data through acertain downlink carrier or transmits data through a certain uplinkcarrier” denotes transmitting or receiving data through control and datachannels provided in a cell corresponding to center frequencies andfrequency bands of the downlink and uplink carriers. Although an LTEmobile communication system is described for convenience of explanation,exemplary embodiments of the present invention may be applied to othertypes of wireless communication systems supporting carrier aggregation.

Exemplary embodiments of the present invention propose UE procedure inreceipt of SCell activation/deactivation command from the eNB. The UEstarts some operations after a predetermined time elapses from thereceipt of an activation command, ends some operations before apredetermined time from the receipt of a deactivation command, and endssome other operations after a predetermined time elapses from thereceipt of the deactivation command. The time point for executing orending a certain operation may differ from the time point for executingor ending another operation, because the activation and deactivationdelay increases when the time points are determined in order of start orend processing delay of the operations. The UE should not start datatransmission/reception in a SCell immediately upon receipt of thecommand from the eNB. This is because it takes additional time toactivate the function blocks for communication in the SCell. Althoughthe function blocks are activated, there may be some delay before thefunction blocks operate normally.

FIG. 4 is a signaling diagram illustrating message flows between UE andeNB for secondary carry activation/deactivation method according to anexemplary embodiment of the present invention.

Referring to FIG. 4, the eNB 403 sends the UE 401 a secondary carriercontrol message (hereinafter, Activation/Deactivation MAC ControlElement (CE) is used interchangeably with secondary carrier controlmessage) including information on the SCell cells to beactivated/deactivated among the configured SCells in N^(th) subframe instep 405. The Activation/Deactivation MAC CE is a MAC CE fixed in sizeof 8 bits and includes seven C fields and one R field. R field denotes areserved field. The C fields are referred to as C7, C6, C5, C4, C3, C2,and C1 (i.e. Ci). Each C field is set to 1 for activation and 0 fordeactivation of SCell i, i.e. secondary carrier. i is an integerselected in the range between 1 and 7 as the secondary carrieridentifier and transmitted by the eNB to the UE along with the secondarycarrier when new secondary carriers are configured.

Upon receipt of the Activation/Deactivation MAC CE, the UE identifiesthe SCell(s) to be activated/deactivated in step 407 and, if a certaincell is to be activated, identifies a first time point in step 409. Thefirst time point indicates an (N+m)^(th) subframe, where m is an integergreater than 1 (e.g. 8). The first time point is for executingoperations to be performed before other operations. m is determined inconsideration of the time taken to decode the receivedActivation/Deactivation MAC CE and analyzes the meaning of the decodedActivation/Deactivation MAC CE and may have a value large enough forterminals having relatively low processing capability. At the first timepoint, i.e. (N+m)^(th) subframe, the UE performs the first operations tobe executed at the first time point in step 411. These operations mayinclude:

Start Channel State Information (CSI) report: the CSI report includesCQI/PMI/RI/PTI necessary for eNB's link adaptation and scheduling.

CQI (Channel Quality Indicator): transmission format recommended tofulfill a bit error rate of 10%.

PMI (Precoding Matrix Index): Index for use in closed-loop spatialmultiplexing.

RI (Rank Indicator): recommended Transmission Rank

PTI (Precoder Type Indicator): recommended precoder type

Start monitoring PDCCH (Physical Downlink Control Channel in SCell

Start transmission of SRS (Sounding Reference Symbol) (only whensounding reference signal is configured)

The eNB sends the UE an Activation/Deactivation MAC CE indicating theSCells to be activated/deactivated among the SCells configured for theUE in P^(th) subframe in step 413.

Upon receipt of the Activation/Deactivation MAC CE, the UE identifiesthe SCell(s) to be activated/deactivated in step 415 and, if a certaincell is to be activated, identifies a second time point in step 417. Thesecond time point indicates a (P+o)^(th) subframe, where o is an integergreater than 1 (e.g. 8). The second time point may be equal to the firsttime point. The UE performs the second operations before the second timepoint, i.e. (P+o)^(th) subframe in step 419. Since these operations arenot associated with the interaction between the UE and eNB, it is notnecessary for the UE to stop the operations at a predetermined timepoint. The operations include:

Stop monitoring PHCCH (Physical Downlink Control Channel) in SCell

Stop transmitting SRS (Sounding Reference Symbol)

The UE executes third operations to be performed at the second timepoint, i.e. (P+o)^(th) subframe, in step 421. These operations includestopping a reporting of CSI. Since this operation is associated with theinteraction between the UE and eNB, the UE should stop the operations ata predetermined time point to avoid performance degradation of the eNBcaused by not stopping the corresponding operations. For example, if theeNB is not aware that the UE has stopped reporting channel stateinformation, the eNB may fail scheduling due to the misjudgment on theUE's channel state.

All of the operations may be performed by following the above describedprocedure.

FIG. 5 is a flowchart illustrating UE procedure for performing firstoperations in a secondary carrier activation/deactivation methodaccording to an exemplary embodiment of the present invention.

Referring to FIG. 5, the UE receives Activation/Deactivation MAC CEhaving an 8-bit bitmap in N^(th) subframe in step 501. Each bit of thebitmap of MAC CE indicates whether to activate or deactivate thecorresponding SCell.

Upon receipt of the Activation/Deactivation MAC CE, the UE determineswhether there is any SCell to be newly activated and, if so, identifiesthe SCell to be activated in step 503. The UE identifies the deactivatedSCells before the receipt of a MAC CE and, when the MAC CE is received,searches the bitmap of the MAC CE for bits representing the deactivatedSCells but marked for activation.

If there is any SCell to be activated, the UE determines the first timepoint and performs the first operations when the first time pointarrives in step 505. As described with reference to FIG. 4, the firsttime point may correspond to an (N+m)^(th) subframe after the timeduration of m subframes elapses from the N^(th) subframe in which the UEreceives the Activation/Deactivation MAC CE. The UE executes theoperations to be performed at the first time point in step 507, i.e. inthe (N+n)^(th) subframe. As described with reference to FIG. 4, theseoperations include:

Start channel State Information (CSI) report

Start monitoring PDCCH (Physical Downlink Control Channel) in SCell

Start transmission of SRS (Sounding Reference Symbol) (only whensounding reference signal is configured)

The value of m is known to both the UE and eNB (e.g. m=8).

FIG. 6 is a flowchart illustrating a UE procedure for performing secondoperations in a secondary carrier activation/deactivation methodaccording to an exemplary embodiment of the present invention.

Referring to FIG. 6, the UE receives the Activation/Deactivation MAC CEincluding 8-bit bitmap in the N^(th) subframe in step 601. Each bit ofthe bitmap of MAC CE indicates whether to activate or deactivate thecorresponding SCell.

Upon receipt of the Activation/Deactivation MAC CE, the UE determineswhether there is any SCell to be deactivated and, if so, identifies theSCell to be deactivated in step 603. The UE identifies the activatedSCells before the receipt of a MAC CE and, when the MAC CE is received,searches the bitmap of the MAC CE for bits representing the activatedSCells but marked for activation.

If there is any SCell to be deactivated, the UE identifies the secondtime point and executes the second operations supposed to be performedbefore the second time point arrives in step 605. As described withreference to FIG. 4, the second operations include:

Stop monitoring PHCCH (Physical Downlink Control Channel) in SCell

Stop transmitting SRS (Sounding Reference Symbol)

The UE waits for the arrival of the second time point in step 607. Asdescribed with reference to FIG. 4, the first time point corresponds tothe (P+o)^(th) subframe after the time duration of o subframes elapsesfrom P^(th) subframe in which the UE receives theActivation/Deactivation MAC CE. The UE executes the third operationssupposed to be performed at the second time point in step 609, i.e. inthe (P+o)^(th) subframe As described with reference to FIG. 4, the thirdoperations include stopping the reporting of CSI. The value of o isknown to both the UE and eNB (e.g. o=8).

FIG. 7 is a block diagram illustrating a configuration of a UE accordingto an exemplary embodiment of the present invention.

Referring to FIG. 7, the UE includes a higher layer device 750 forgenerating data to be transmitted and processing the received data, acontrol message processor 707 for processing control messages receivedand to be transmitted, a multiplexer/demultiplexer 703 for multiplexingdata and control signals to be transmitted via the transceiver 701 andfor demultiplexing the received data and controls signals to bedelivered to the control message controller 707 and the higher layerdevice 705 respectively under the control of the control unit 709.

According an exemplary embodiment of the present invention, when theActivation/Deactivation MAC CE for activation is received, the controlmessage processor 707 notifies the SCell activation/deactivationprocessor 711 of the receipt of MAC CE such that the SCellactivation/deactivation processor 711 determines the first time pointand, when the first time point arrives, notifies the controller 709 andthe control message processor 707 of the operations to be executed atthe first time point. When the Activation/Deactivation MAC CE fordeactivation is received, the control message processor 707 notifies theSCell activation/deactivation processor 711 of the receipt of the MAC CEsuch that the SCell activation/deactivation processor 711 determines thesecond time point and notifies the controller 709 and the controlmessage processor 707 of the operations to be executed before and whenthe second time point arrives.

Although the description is directed to the UE composed of a pluralityof function blocks performing different functions, exemplary embodimentsof the present invention is not limited thereto. For example, the UE maybe implemented with a transceiver and an integrated controller. In thiscase, when a secondary carrier control message is received from the eNB,the controller checks the secondary carriers to beactivated/deactivated. The controller may monitor the arrival of thefirst time point and control to perform the first operations when thefirst time point arrives.

The first time point is the time after the time duration correspondingto 8 subframes elapses from the receipt of the secondary carrier controlmessage. The first operations may include at least one of CSI reportinitiation, PDCCH monitoring initiation on secondary carrier, and SRStransmission initiation.

The controller may also control to perform the second operations beforethe second time point arrives and the third operations at the secondtime point when a secondary carrier deactivation command is analyzed.

According to an exemplary embodiment of the present invention, thesecond time point may be equal to the first time point, i.e. the timeafter the time duration corresponding to 8 subframes elapses from thereceipt of the secondary carrier control message. The second operationsmay include at least one of PDCCH monitoring termination on thesecondary carrier and SRS transmission termination.

As described above, the secondary carrier activation/deactivation methodand apparatus according to exemplary embodiments of the presentinvention controls specific operations to be executed at predeterminedtime points in association with the activation and deactivation ofSCells in the mobile communication supporting carrier aggregation,thereby preventing a UE from malfunctioning.

The secondary carrier activation/deactivation method and apparatusaccording to exemplary embodiments of the present invention is alsocapable of guaranteeing the successful execution of operations necessaryin activation and deactivation of SCells, resulting in completion ofactivation and deactivation without error.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentinvention as defined by the appended claims and their equivalents.

What is claimed is:
 1. A method for deactivating at least one secondarycell of a user equipment (UE) in a mobile communication systemsupporting carrier aggregation, the method comprising: receiving controlinformation including a deactivation command of the at least onesecondary cell in a first sub-frame from a base station; performing afirst operation corresponding to the deactivation command of the atleast one secondary cell in a second sub-frame; and performing at leastone second operation corresponding to the deactivation command of the atleast one secondary cell no later than the second sub-frame.
 2. Themethod of claim 1, wherein a difference of sub-frames between the firstsub-frame and the second sub-frame is
 8. 3. The method of claim 1,wherein the first operation is a termination of a channel stateinformation report.
 4. The method of claim 3, wherein the at least onechannel state information report comprises at least one of a channelquality indicator, a precoding matrix index, a rank indicator, and aprecoder type indicator.
 5. The method of claim 1, wherein the at leastone second operation comprises at least one of a termination of physicaldownlink control channel monitoring and a termination of a soundingreference signal transmission of the at least one secondary cell.
 6. Auser equipment (UE) for deactivating at least one secondary cell in amobile communication system supporting carrier aggregation, the UEcomprising: a transceiver for transmitting and receiving signals with abase station; and a controller configured to receive control informationincluding a deactivation command of the at least one secondary cell in afirst sub-frame from a base station, to perform a first operationcorresponding to the deactivation command of the at least one secondarycell in a second sub-frame, and to perform at least one second operationcorresponding to the deactivation command of the at least one secondarycell no later than the second sub-frame.
 7. The UE of claim 6, wherein adifference of sub-frames between the first sub-frame and the secondsub-frame is
 8. 8. The UE of claim 6, wherein the first operation is atermination of a channel state information report.
 9. The UE of claim 8,wherein the at least one channel state information report comprises atleast one of a channel quality indicator, a precoding matrix index, arank indicator, and a precoder type indicator.
 10. The UE of claim 6,wherein the at least one second operation comprises at least one of atermination of physical downlink control channel monitoring and atermination of a sounding reference signal transmission of the at leastone secondary cell.
 11. A base station for controlling deactivation ofsecondary cells in a mobile communication system supporting carrieraggregation, the base station comprising: a transceiver for transmittingand receiving signals with a user equipment (UE); and a controllerconfigured to generate control information including a deactivationcommand of at least one secondary cell, to transmit the controlinformation in a first subframe to the UE, to receive a channel stateinformation (CSI) report on the at least one secondary cell in a secondsubframe, and to terminate a reception of sound reference signal for theat least one cell no later than the second subframe.
 12. The basestation of claim 11, wherein a difference of sub-frames between thefirst sub-frame and the second sub-frame is
 8. 13. The base station ofclaim 11, wherein the CSI report comprises at least one of a channelquality indicator, a precoding matrix index, a rank indicator, and aprecoder type indicator.